You can now lock the mouse cursor while connected to a remote machine. This makes it possible to play 3D first person shooters and certain 3D graphics apps that rely on mouse delta movements.  

To enable mouse pointer locking, connect to the remote computer using Fluid and then click Remote -> Lock Mouse Cursor. 

To unlock the cursor press and hold the ESC key on your keyboard.

Playing DOOM Eternal over Jump Desktop. Warning: Graphic Content.